sparc32: get rid of odd callers of copy_regset_to_user()

the life is much simpler if copy_regset_to_user() (and ->get())
gets called only with pos == 0; sparc32 PTRACE_GETREGS and
PTRACE_GETFPREGS are among the few things that use it to fetch
pieces of regset _not_ starting at the beginning.  It's actually
easier to define a separate regset that would provide what
we need, rather than trying to cobble that from the one
PTRACE_GETREGSET uses.

Extra ->get() instances do not amount to much code and once
we get the conversion of ->get() to new API (dependent upon the
lack of weird callers of ->get()) they'll shrink a lot, along
with the rest of ->get() instances...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/sparc/kernel/ptrace_32.c

@@ -99,15 +99,13 @@ static int genregs32_get(struct task_struct *target,
 	if (ret || !count)
 		return ret;
 
-	if (pos < 32 * sizeof(u32)) {
-		if (regwindow32_get(target, regs, uregs))
-			return -EFAULT;
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					  uregs,
-					  16 * sizeof(u32), 32 * sizeof(u32));
-		if (ret || !count)
-			return ret;
-	}
+	if (regwindow32_get(target, regs, uregs))
+		return -EFAULT;
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  uregs,
+				  16 * sizeof(u32), 32 * sizeof(u32));
+	if (ret)
+		return ret;
 
 	uregs[0] = regs->psr;
 	uregs[1] = regs->pc;
@@ -288,6 +286,73 @@ static const struct user_regset sparc32_regsets[] = {
 	},
 };
 
+static int getregs_get(struct task_struct *target,
+			 const struct user_regset *regset,
+			 unsigned int pos, unsigned int count,
+			 void *kbuf, void __user *ubuf)
+{
+	const struct pt_regs *regs = target->thread.kregs;
+	u32 v[4];
+	int ret;
+
+	if (target == current)
+		flush_user_windows();
+
+	v[0] = regs->psr;
+	v[1] = regs->pc;
+	v[2] = regs->npc;
+	v[3] = regs->y;
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  v,
+				  0 * sizeof(u32), 4 * sizeof(u32));
+	if (ret)
+		return ret;
+
+	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  regs->u_regs + 1,
+				  4 * sizeof(u32), 19 * sizeof(u32));
+}
+
+static int getfpregs_get(struct task_struct *target,
+			const struct user_regset *regset,
+			unsigned int pos, unsigned int count,
+			void *kbuf, void __user *ubuf)
+{
+	const unsigned long *fpregs = target->thread.float_regs;
+	int ret = 0;
+
+#if 0
+	if (target == current)
+		save_and_clear_fpu();
+#endif
+
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  fpregs,
+				  0, 32 * sizeof(u32));
+	if (ret)
+		return ret;
+	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				  &target->thread.fsr,
+				  32 * sizeof(u32), 33 * sizeof(u32));
+	if (ret)
+		return ret;
+	return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
+				  33 * sizeof(u32), 68 * sizeof(u32));
+}
+
+static const struct user_regset ptrace32_regsets[] = {
+	[REGSET_GENERAL] = {
+		.n = 19, .size = sizeof(u32), .get = getregs_get,
+	},
+	[REGSET_FP] = {
+		.n = 68, .size = sizeof(u32), .get = getfpregs_get,
+	},
+};
+
+static const struct user_regset_view ptrace32_view = {
+	.regsets = ptrace32_regsets, .n = ARRAY_SIZE(ptrace32_regsets)
+};
+
 static const struct user_regset_view user_sparc32_view = {
 	.name = "sparc", .e_machine = EM_SPARC,
 	.regsets = sparc32_regsets, .n = ARRAY_SIZE(sparc32_regsets)
@@ -327,15 +392,10 @@ long arch_ptrace(struct task_struct *child, long request,
 
 	switch(request) {
 	case PTRACE_GETREGS: {
-		ret = copy_regset_to_user(child, view, REGSET_GENERAL,
-					  32 * sizeof(u32),
-					  4 * sizeof(u32),
-					  &pregs->psr);
-		if (!ret)
-			copy_regset_to_user(child, view, REGSET_GENERAL,
-					    1 * sizeof(u32),
-					    15 * sizeof(u32),
-					    &pregs->u_regs[0]);
+		ret = copy_regset_to_user(child, &ptrace32_view,
+					  REGSET_GENERAL, 0,
+					  19 * sizeof(u32),
+					  pregs);
 		break;
 	}
 
@@ -353,23 +413,10 @@ long arch_ptrace(struct task_struct *child, long request,
 	}
 
 	case PTRACE_GETFPREGS: {
-		ret = copy_regset_to_user(child, view, REGSET_FP,
-					  0 * sizeof(u32),
-					  32 * sizeof(u32),
-					  &fps->regs[0]);
-		if (!ret)
-			ret = copy_regset_to_user(child, view, REGSET_FP,
-						  33 * sizeof(u32),
-						  1 * sizeof(u32),
-						  &fps->fsr);
-
-		if (!ret) {
-			if (__put_user(0, &fps->fpqd) ||
-			    __put_user(0, &fps->flags) ||
-			    __put_user(0, &fps->extra) ||
-			    clear_user(fps->fpq, sizeof(fps->fpq)))
-				ret = -EFAULT;
-		}
+		ret = copy_regset_to_user(child, &ptrace32_view,
+					  REGSET_FP, 0,
+					  68 * sizeof(u32),
+					  fps);
 		break;
 	}